ISO Metric Fine Thread, pitch 1 and 1.25 · DIN 13-5

M39 × 1 Thread: Pitch, Tap Drill & Dimensions

M39 × 1 is an ISO metric fine thread with a 1 mm pitch. The tap drill is 38 mm, and the internal minor diameter D1 is 37.917 mm.

Profile shape (schematic, not to scale)
M39 × 1 thread dimensions
Nominal (major) diameter39 mm
Pitch1 mm (fine)
Tap drill (D − P)38 mm
Pitch diameter d2 / D238.35 mm
Minor diameter, external d337.773 mm
Minor diameter, internal D137.917 mm
Thread depth, external h30.613 mm
Flank angle60°
Clearance hole (fine / medium / coarse)40 / 42 / 45 mm

Common questions

What size drill do I use to tap M39 × 1?

Use a 38 mm drill. This is the standard tap drill for M39 × 1; for hard materials or deep threads a slightly larger drill reduces tapping torque.

What is the pitch of M39 × 1?

The pitch of M39 × 1 is 1 mm (fine), meaning the thread advances that distance in one full turn.

Where can I find other ISO Metric Fine Thread, pitch 1 and 1.25 sizes?

The full ISO Metric Fine Thread, pitch 1 and 1.25 table, with every size and a live filter, is on its standard page, and the Thread Finder searches all 73 standards at once.

Reference values; computed values use the ISO basic profile. Verify against the current standard before production use.

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